It is a generally accepted standard that editors should attempt to follow, though it is best treated with common sense, and occasional exceptions may apply. Any substantive edit to this page should reflect consensus. When in doubt, discuss first on the talk page.

This page in a nutshell: This guideline discusses how to identify reliable sources. The policy on sourcing is Wikipedia:Verifiability. This requires inline citations for any material challenged or likely to be challenged, and for all quotations.

The guideline in this page discusses the reliability of various types of sources. The policy on sourcing is Wikipedia:Verifiability, which requires inline citations for any material challenged or likely to be challenged, and for all quotations. The policy is strictly applied to all material in the mainspace—articles, lists, and sections of articles—without exception, and in particular to biographies of living persons, which states:

Contentious material about living persons (or, in some cases, recently deceased) that is unsourced or poorly sourced—whether the material is negative, positive, neutral, or just questionable—should be removed immediately and without waiting for discussion.

Overview

Source reliability falls on a spectrum: highly reliable sources, clearly unreliable sources, and many in the middle. Editors must use their judgment to draw the line between usable and unreliable sources.

Articles should be based on reliable, third-party, published sources with a reputation for fact-checking and accuracy. This means that we publish the opinions only of reliable authors, and not the opinions of Wikipedians who have read and interpreted primary source material for themselves. The following examples cover only some of the possible types of reliable sources and source reliability issues, and are not intended to be exhaustive. Proper sourcing always depends on context; common sense and editorial judgment are an indispensable part of the process.

Definition of a source

The word "source" when citing sources on Wikipedia has three related meanings:

Any of the three can affect reliability. Reliable sources may be published materials with a reliable publication process, authors who are regarded as authoritative in relation to the subject, or both. These qualifications should be demonstrable to other people.

Definition of published

The term "published" is most commonly associated with text materials, either in traditional printed format or online. However, audio, video, and multimedia materials that have been recorded then broadcast, distributed, or archived by a reputable party may also meet the necessary criteria to be considered reliable sources. Like text sources, media sources must be produced by a reliable third party and be properly cited. Additionally, an archived copy of the media must exist. It is convenient, but by no means necessary, for the archived copy to be accessible via the Internet.

Context matters

The reliability of a source depends on context. Each source must be carefully weighed to judge whether it is reliable for the statement being made in the Wikipedia article and is an appropriate source for that content. In general, the more people engaged in checking facts, analyzing legal issues, and scrutinizing the writing, the more reliable the publication. Information provided in passing by an otherwise reliable source that is not related to the principal topics of the publication may not be reliable; editors should cite sources focused on the topic at hand where possible. Sources should directly support the information as it is presented in the Wikipedia article.

Age matters

Especially in scientific and academic fields, older sources may be inaccurate because new information has been brought to light, new theories proposed, or vocabulary changed. In areas like politics or fashion, laws or trends may make older claims incorrect. Be sure to check that older sources have not been superseded, especially if it is likely the new discoveries or developments have occurred in the last few years. In particular, newer sources are generally preferred in medicine.

Sometimes sources are too new to use, such as with breaking news (where later reports might be more accurate), and primary sources which purport to debunk a long-standing consensus or introduce a new discovery (in which case awaiting studies that attempt to replicate the discovery might be a good idea, or reviews that validate the methods used to make the discovery).

With regard to historical events, older reports (closer to the event, but not too close such that they are prone to the errors of breaking news) tend to have the most detail, and are less likely to have errors introduced by repeated copying and summarizing. However, newer secondary and tertiary sources may have done a better job of collecting more reports from primary sources and resolving conflicts, applying modern knowledge to correctly explain things that older sources could not have, or remaining free of bias that might affect sources written while any conflicts described were still active or strongly felt.

Sources of any age may be prone to recentism, and this needs to be balanced out by careful editing.

Some types of sources

Many Wikipedia articles rely on scholarly material. When available, academic and peer-reviewed publications, scholarly monographs, and textbooks are usually the most reliable sources. However, some scholarly material may be outdated, in competition with alternative theories, or controversial within the relevant field. Try to cite current scholarly consensus when available, recognizing that this is often absent. Reliable non-academic sources may also be used in articles about scholarly issues, particularly material from high-quality mainstream publications. Deciding which sources are appropriate depends on context. Material should be attributed in-text where sources disagree.

Scholarship

Articles should rely on secondary sources whenever possible. For example, a review article, monograph, or textbook is better than a primary research paper. When relying on primary sources, extreme caution is advised: Wikipedians should never interpret the content of primary sources for themselves. See Wikipedia:No original research and Wikipedia:Neutral point of view.

Material such as an article, book, monograph, or research paper that has been vetted by the scholarly community is regarded as reliable, where the material has been published in reputable peer-reviewed sources or by well-regarded academic presses.

Completed dissertations or theses written as part of the requirements for a PhD, and which are publicly available (most via interlibrary loan or from Proquest), can be used but care should be exercised, as they are often, in part, primary sources. Some of them will have gone through a process of academic peer reviewing, of varying levels of rigor, but some will not. If possible, use theses that have been cited in the literature; supervised by recognized specialists in the field; or reviewed by third parties. Dissertations in progress have not been vetted and are not regarded as published and are thus not reliable sources as a rule. Some theses are later published in the form of scholarly monographs or peer reviewed articles, and, if available, these are usually preferable to the original thesis as sources. Masters dissertations and theses are considered reliable only if they can be shown to have had significant scholarly influence.

One can confirm that discussion of the source has entered mainstream academic discourse by checking the scholarly citations it has received in citation indexes. A corollary is that journals not included in a citation index, especially in fields well covered by such indexes, should be used with caution, though whether it is appropriate to use will depend on the context.

Isolated studies are usually considered tentative and may change in the light of further academic research. If the isolated study is a primary source, it should generally not be used if there are secondary sources that cover the same content. The reliability of a single study depends on the field. Avoid undue weight when using single studies in such fields. Studies relating to complex and abstruse fields, such as medicine, are less definitive and should be avoided. Secondary sources, such as meta-analyses, textbooks, and scholarly review articles are preferred when available, so as to provide proper context.

Care should be taken with journals that exist mainly to promote a particular point of view. A claim of peer review is not an indication that the journal is respected, or that any meaningful peer review occurs. Journals that are not peer reviewed by the wider academic community should not be considered reliable, except to show the views of the groups represented by those journals.[notes 1]

In recent years there has been an explosion in new journals of very low quality that have only token peer-review if any (see predatory journals). They simply publish whatever is submitted if the author is willing to pay a fee. Some go so far as to mimic the names of established journals (see hijacked journals).[1][2][3][4][5] The lack of reliable peer review implies that articles in such journals should be treated similarly to self-published sources. If you are unsure about the quality of a journal, check that the editorial board is based in a respected accredited university, and that it is included in the relevant high-quality citation index—be wary of indexes that merely list almost all publications, and do not vet the journals they list.

News organizations

News sources often contain both factual content and opinion content. "News reporting" from well-established news outlets is generally considered to be reliable for statements of fact (though even the most reputable reporting sometimes contains errors). News reporting from less-established outlets is generally considered less reliable for statements of fact. Most newspapers also reprint items from news agencies such as BBC News, Reuters, Interfax, Agence France-Presse, United Press International or the Associated Press, which are responsible for accuracy. The agency should be cited in addition to the newspaper that reprinted it.

When taking information from opinion content, the identity of the author may help determine reliability. The opinions of specialists and recognized experts are more likely to be reliable and to reflect a significant viewpoint.[notes 2] If the statement is not authoritative, attribute the opinion to the author in the text of the article and do not represent it as fact. Reviews for books, movies, art, etc. can be opinion, summary or scholarly pieces.[7][8]

Scholarly sources and high-quality non-scholarly sources are generally better than news reports for academic topics. Press releases from the organizations or journals are often used by newspapers with minimal change; such sources are churnalism and should not be treated differently than the underlying press release. Occasionally, some newspapers still have specialist reporters who are citable by name. With regard to biomedical articles, see also Wikipedia:Identifying reliable sources (medicine).

The reporting of rumors has a limited encyclopedic value, although in some instances verifiable information about rumors may be appropriate (i.e. if the rumors themselves are noteworthy, regardless of whether or not they are true). Wikipedia is not the place for passing along gossip and rumors.

Some news organizations have used Wikipedia articles as a source for their work. Editors should therefore beware of circular sourcing.[notes 3]

Whether a specific news story is reliable for a fact or statement should be examined on a case-by-case basis.

Multiple sources should not be asserted for any wire service article. Such sources are essentially a single source.

Some news organizations do not publish their editorial policies.

One signal that a news organization engages in fact-checking and has a reputation for accuracy is the publication of corrections.

Vendor and e-commerce sources

Although the content guidelines for external links prohibits linking to "Individual web pages that primarily exist to sell products or services," inline citations may be allowed to e-commerce pages such as that of a book on a bookseller's page or an album on its streaming-music page, in order to verify such things as titles and running times. Journalistic and academic sources are preferable, however, and e-commerce links should be replaced with non-commercial reliable sources if available.

Rankings proposed by vendors (such as bestseller lists at Amazon) usually have at least one of the following problems:

It may be impossible to provide a stable source for the alleged ranking;

When only self-published by the vendor, i.e. no reliable third-party source confirming the ranking as being relevant, the ranking would usually carry insufficient weight to be mentioned in any article.

For such reasons such rankings are usually avoided as Wikipedia content.

Biased or opinionated sources

Wikipedia articles are required to present a neutral point of view. However, reliable sources are not required to be neutral, unbiased, or objective. Sometimes non-neutral sources are the best possible sources for supporting information about the different viewpoints held on a subject.

Common sources of bias include political, financial, religious, philosophical, or other beliefs. Although a source may be biased, it may be reliable in the specific context. When dealing with a potentially biased source, editors should consider whether the source meets the normal requirements for reliable sources, such as editorial control and a reputation for fact-checking. Editors should also consider whether the bias makes it appropriate to use in-text attribution to the source, as in "Feminist Betty Friedan wrote that...", "According to the Marxist economist Harry Magdoff...," or "Conservative Republican presidential candidate Barry Goldwater believed that...".

Questionable and self-published sources

Questionable sources

Questionable sources are those with a poor reputation for checking the facts, or with no editorial oversight. Such sources include websites and publications expressing views that are widely acknowledged as extremist, that are promotional in nature, or that rely heavily on rumors and personal opinions.[9] Questionable sources are generally unsuitable for citing contentious claims about third parties, which includes claims against institutions, persons living or dead, as well as more ill-defined entities. The proper uses of a questionable source are very limited.

Beware of sources that sound reliable but do not have the reputation for fact-checking and accuracy that WP:RS requires.[10] The Journal of 100% Reliable Factual Information might have a reputation for "predatory" behavior, which includes questionable business practices and/or peer-review processes that raise concerns about the reliability of their journal articles.[11][12]

Self-published sources (online and paper)

Anyone can create a personal web page or publish their own book and claim to be an expert in a certain field. For that reason, self-published media are largely not acceptable. Self-published books and newsletters, personal pages on social networking sites, tweets, and posts on Internet forums are all examples of self-published media.

Exceptions

Content from a collaboratively created website may be acceptable if the content was authored by, and is credited to, credentialed members of the site's editorial staff.

Some news outlets host interactive columns they call "blogs", and these may be acceptable as sources if the writers are professional journalists or professionals in the field on which they write, and the blog is subject to the news outlet's full editorial control. Posts left by readers may never be used as sources (see WP:Verifiability § Newspaper and magazine blogs).

Self-published material may sometimes be acceptable when its author is an established expert whose work in the relevant field has been published by reliable third-party publications. Such material, although written by an established author, likely lacks the fact checking that publishers provide. Avoid using them to source extraordinary claims. Self-published information should never be used as a third-party source about another living person, even if the author is a well-known professional researcher or writer (see WP:Biographies of living persons § Reliable sources).

Self-published and questionable sources as sources on themselves

Self-published or questionable sources may be used as sources of information about themselves, especially in articles about themselves, without the requirement that they be published experts in the field, so long as the following criteria are met:

Reliability in specific contexts

Biographies of living persons

Editors must take particular care when writing biographical material about living persons. Contentious material about a living person that is unsourced or poorly sourced should be removed immediately; do not move it to the talk page. This applies to any material related to living persons on any page in anynamespace, not just article space.

Reputable tertiary sources, such as introductory-level university textbooks, almanacs, and encyclopedias, may be cited. However, although Wikipedia articles are tertiary sources, Wikipedia employs no systematic mechanism for fact checking or accuracy. Thus, Wikipedia articles (and Wikipedia mirrors) in themselves are not reliable sources for any purpose (except as sources on themselves per WP:SELFSOURCE). Because Wikipedia forbids original research, there is nothing reliable in it that is not citable with something else.

Primary sources are often difficult to use appropriately. Although they can be both reliable and useful in certain situations, they must be used with caution in order to avoid original research. Although specific facts may be taken from primary sources, secondary sources that present the same material are preferred. Large blocks of material based purely on primary sources should be avoided. All interpretive claims, analyses, or synthetic claims about primary sources must be referenced to a secondary source, rather than original analysis of the primary-source material by Wikipedia editors.

Medical claims

Ideal sources for biomedical assertions include general or systematic reviews in reliable, third-party, published sources, such as reputable medical journals, widely recognised standard textbooks written by experts in a field, or medical guidelines and position statements from nationally or internationally reputable expert bodies. It is vital that the biomedical information in all types of articles be based on reliable, third-party, published sources and accurately reflect current medical knowledge.

Quotations

The accuracy of quoted material is paramount and the accuracy of quotations from living persons is especially sensitive. To ensure accuracy, the text of quoted material is best taken from (and cited to) the original source being quoted. If this is not possible, then the text may be taken from a reliable secondary source (ideally one that includes a citation to the original). No matter where you take the quoted text from, it is important to make clear the actual source of the text, as it appears in the article.

Partisan secondary sources should be viewed with suspicion as they may misquote or quote out of context. In such cases, look for neutral corroboration from another source.

Any analysis or interpretation of the quoted material, however, should rely on a secondary source (See: WP:No original research).

Academic consensus

A statement that all or most scientists or scholars hold a certain view requires reliable sourcing that directly says that all or most scientists or scholars hold that view. Otherwise, individual opinions should be identified as those of particular, named sources. Editors should avoid original research especially with regard to making blanket statements based on novel syntheses of disparate material. Stated simply, any statement in Wikipedia that academic consensus exists on a topic must be sourced rather than being based on the opinion or assessment of editors. Review articles, especially those printed in academic review journals that survey the literature, can help clarify academic consensus.

Usage by other sources

How accepted, high-quality reliable sources use a given source provides evidence, positive or negative, for its reliability and reputation. The more widespread and consistent this use is, the stronger the evidence. For example, widespread citation without comment for facts is evidence of a source's reputation and reliability for similar facts, whereas widespread doubts about reliability weigh against it. If outside citation is the main indicator of reliability, particular care should be taken to adhere to other guidelines and policies, and to not represent unduly contentious or minority claims. The goal is to reflect established views of sources as far as we can determine them.

Statements of opinion

Some sources may be considered reliable for statements as to their author's opinion, but not for statements asserted as fact. For example, an inline qualifier might say "[Author XYZ] says....". A prime example of this is opinion pieces in sources recognized as reliable. When using them, it is best to clearly attribute the opinions in the text to the author and make it clear to the reader that they are reading an opinion.

Note that otherwise reliable news sources—for example, the website of a major news organization—that publish in a blog-style format for some or all of their content may be as reliable as if published in a more "traditional" 20th-century format.

Breaking news

Breaking news reports often contain serious inaccuracies. As an electronic publication, Wikipedia can and should be up to date, but Wikipedia is not a newspaper and it does not need to go into all details of a current event in real time. It is better to wait a day or two after an event before adding details to the encyclopedia, than to help spread potentially false rumors. This gives journalists time to collect more information and verify claims, and for investigative authorities to make official announcements. The On the MediaBreaking News Consumer's Handbook contains several suggestions to avoid unreliable information, such as distrusting anonymous sources, distrusting unconfirmed reports and those attributed to other news media, seeking multiple sources, seeking eyewitness reports, being wary of potential hoaxes, and being skeptical of reports of possible additional attackers in mass shootings.

Claims sourced to initial news reports should be replaced with better-researched ones as soon as possible, especially where incorrect information was imprudently added. All breaking news stories, without exception, are primary sources, and must be treated with caution per WP:PSTS.

When editing articles covering current events, also keep in mind the essay on recentism bias.

{{current}}, {{recent death}}, or other current event-related templates may be added to the top of articles concerning breaking news, to alert readers that some information may be inaccurate, and to draw attention to the need to add improved sources as they become available. Keep in mind, however, that these current event-related templates are not intended to be used to mark an article that merely has recent news articles about the topic; if it were, hundreds of thousands of articles would have this template, with no informational consequence (see also Wikipedia:No disclaimers in articles).

Notes

^Please keep in mind that any exceptional claim would require exceptional sources, and this is policy.

^A variety of these incidents have been documented by Private Eye and others and discussed on Wikipedia, where incorrect details from articles added as vandalism or otherwise have appeared in newspapers

^Miller, Laura (October 16, 2011). "'Sybil Exposed': Memory, lies and therapy". Salon. Salon Media Group. Retrieved October 17, 2011. [Debbie Nathan] also documents a connection between Schreiber and Terry Morris, a 'pioneer' of this [human interest] genre who freely admitted to taking 'considerable license with the facts that are given to me.'